1. Field of the Invention
The present invention belongs to the technical field of a liquid crystal device according to the active-matrix driving method by thin film transistor (hereafter referred to as xe2x80x9cTFTxe2x80x9d whenever appropriate) driving, and particularly belongs to the technical field of liquid crystal devices of the format wherein a light-shielding film is provided to the lower side of TFTs, and used for liquid crystal projectors and the like.
2. Description of Related Art
Conventionally, in cases wherein such liquid crystal devices are used in liquid crystal projectors and the like as light valves, generally, projected light is cast in from the side of an opposite substrate positioned in a manner opposing a TFT array substrate across a liquid crystal layer. Now, in the event that projected light is cast into a channel area comprised of an a-Si (amorphous silicone) film or a p-Si (poly-silicone) film of a TFT, a photo-current is undesirably generated in this area due to photo-electric conversion effects, and the transistor properties of the TFT deteriorate. Accordingly, generally a light-shielding film formed of a metal material such as Cr (chromium), resin black, or the like is formed at each position facing each TFT on the opposite substrate. The light-shielding films serve to shield light to the opening area (namely, the area transmitting projected light) of each pixel by defining the opening area, and also having the functions of improving contrast, preventing mixing of color materials, and so forth, in addition to shielding light from the p-Si layer of the TFT.
In this type of liquid crystal device, particularly in the event that positive stagger type or coplanar type, a-Si or p-Si TFTs having a top-gate structure (namely, a structure wherein the gate electrode is provided above the channel on the TFT array substrate) are used, there is the need to prevent part of the projected light being cast into the TFT channel from the side of the TFT array substrate as returning light from the projection optical system within the liquid crystal projector. In the same way, there is the need to prevent reflected light from the surface of the TFT array substrate at the time the projected light passes through, or part of projected light cast from other liquid crystal devices passing through the projection optical system in the event that a plurality of liquid crystal devices are combined for color, being cast into the TFT channel from the side of the TFT array substrate as returning light. To this end, Japanese Unexamined Patent Publication No. 9-127497, Japanese Examined Patent Publication No. 3-52611, Japanese Unexamined Patent Publication No. 3-125123, Japanese Unexamined Patent Publication No. 8-171101, and so forth propose a liquid crystal device wherein a light-shielding film is formed of a non-transparent metal with a high melting point at a position facing a TFT on the TFT array substrate formed of a quartz substrate or the like (namely, to the lower side of the TFT).
On the other hand, with such liquid crystal devices, a method is generally used wherein pixel electrodes are provided with a storage capacitor in order to extend the amount of time that voltage is maintained to the pixel electrodes with regard to the time wherein image signals are supplied to the pixel electrodes by setting the TFTs in a conducting state by means of applying scanning signals to the gate electrodes, namely, so that the liquid crystal driving voltage can be applied in a sufficient amount of time even in the event that the duty ratio is small. In such a case, a portion of capacitance lines formed parallel to scanning lines generally comprise other storage capacitor electrodes.
There is a strong general request for improvement of image quality for liquid crystal devices, and it is important to raise the driving frequencies of liquid crystal devices to this end.
However, in order to provide a storage capacitor to the pixel electrodes as described above, in the event that a high-temperature process including a process wherein the substrate temperature is subjected to a high temperature such as 900 degrees or the like, capacitance lines including the one storage capacitor electrode are formed of a poly-silicone film as with the scanning lines, so lowering resistance is difficult as compared with wirings formed of low-resistance metal film such as Al as data lines, for example. Accordingly, the resistance and time-constant of the capacitance lines increases, and the potential of the capacitance lines fluctuates in the capacitance lines wired in a manner intersecting underneath a plurality of data lines, owing to capacitance coupling with each data line, resulting in a problem that the image quality deteriorates due to sideways cross-talk, ghosting, and the like.
More specifically, as shown in FIG. 20, in the event that an image 801 drawn with a gray background and a highly-contrasted black portion is to be displayed, in the case that image signals of a voltage (here, a voltage corresponding with black) partially differing from the image signal voltage (here, a voltage corresponding with gray) provided to other pixels in a pixel line along a scanning line are provided, writing is performed to each pixel in the pixel line before the potential fluctuation of the capacitance line owing to such capacitance coupling stabilizes. Accordingly, in the actually displayed image 802, there is insufficient voltage at the pixels to the right and left of the pixel to which the image signal of a partially different voltage to be displayed black is provided, resulting in a phenomena wherein the entire line to be displayed as gray turns whitish, namely, sideways cross-talk, ghosting, or the like, is generated.
In this case, particularly, the closer the point wherein image signals of a voltage partially different to be displayed black are provided is to the end of completing writing to each scanning line, namely, the closer the pixel to be displayed black is to the end of a line opposite to the side from which scanning signals are supplied in the event that scanning signals are supplied to one scanning line from the right or the left, or the closer to the center the pixel is in the case that scanning signals are supplied from both ends, the more writing is performed to each pixel in the pixel line before the potential fluctuation of the capacitance line owing to such capacitance coupling stabilizes, so sideways cross-talk, ghosting, or the like, is generated more easily.
Such sideways cross-talk, ghosting, or the like, is generated more easily in the event that the driving frequency increases with liquid crystal devices of types such as so-called XGA, SXGA, and so forth, since the time constant of the capacitance line becomes relatively large. Further, in the event of performing pre-charging wherein pre-charging signals of a certain voltage level are each supplied to data lines before the image signals so that image signal voltage can be written to the data lines with a small load, there is the need to secure a horizontal retrace line period of a certain length for pre-charging, so time for the potential fluctuation of the capacitance line owing to capacitance coupling to stabilize cannot be sufficiently secured following providing the image signal with a partially different voltage at a point close to the point of completing writing in each scanning line. Accordingly, there is a problem in that it is difficult to present the above-described sideways cross-talk, ghosting, or the like, when performing pre-charging.
In order to solve the problem of such sideways cross-talk, ghosting, or the like, the data line inversion driving method wherein the polarity of driving voltage applied to the liquid crystal is inverted for each data line (1S inversion driving method) and the dot inversion driving method wherein each dot is inverted are effective, but these methods generate intense generation of disclination (defective alignment) of the liquid crystal following the data lines and scanning lines, causing display deterioration, so these methods are not practical under the basic requests of increasing the rate of opening of the pixel area, in particular.
The present invention has been made in light of the above-described problems, and it is an object thereof to provide a liquid crystal device capable of high-quality image display by means of a relatively simple configuration using a storage capacitor and a light-shielding film.
In order to solve the above problems, a first liquid crystal device according to the present invention may consist of: a plurality of pixel electrodes arrayed in a matrix on one substrate of a pair of substrates between which a liquid crystal is held; a plurality of thin film transistors, each of which drives the plurality of pixel electrodes; a plurality of data lines and plurality of scanning lines, each connected to the plurality of thin film transistors and intersecting with each other; a plurality of capacitance lines arrayed along with the plurality of scanning lines and each extending in a direction intersecting with the plurality of data lines, wherein each provides a storage capacitor to the plurality of pixel electrodes; a plurality of light-shielding films, each extending in a direction intersecting with the plurality of data lines, and provided at positions so as to cover at least the channel area of the plurality of thin film transistors when viewed from the side of the one substrate, and at positions each at least partially facing the plurality of capacitance lines, wherein each is electrically connected with the plurality of capacitance lines for every pixel or plurality of pixels in a direction intersecting with the plurality of data lines; and a first inter-layer insulating film existing between the plurality of light-shielding films and the thin-film transistors.
According to the first liquid crystal device according to the present invention, a plurality of capacitance lines, each of which provides a storage capacitor to a plurality of pixel electrodes, are arrayed along with the plurality of scanning lines and each extending in a direction intersecting with the plurality of data lines (namely, parallel with or generally parallel with the respective scanning lines). On the other hand, a plurality of light-shielding films, each extends in a direction intersecting with the plurality of data lines (namely, parallel with or generally parallel with the respective scanning lines), are provided on one substrate at positions so as to cover at least the channel area of the plurality of thin film transistors when viewed from the side of the one substrate. Accordingly, the channel area of the thin film transistors is shielded from light by multiple light-shielding films regarding returning light cast in from the side of the one substrate, thereby preventing deterioration of the properties of the thin film transistors due to returning light and the like.
The plurality of light-shielding films is provided on one substrate at positions where each at least partially facing the plurality of capacitance lines, and each is electrically connected with the plurality of capacitance lines for every pixel or plurality of pixels in a direction intersecting with the plurality of data lines. Accordingly, the resistance of the capacitance line can be markedly lowered by the resistance of the plurality of light-shielding films. For example, by forming the capacitance lines from a poly-silicone film and forming the plurality of light-shielding films from a conductive metal film with a high melting point, the resistance of the capacitance lines in the direction parallel to the scanning lines can be governed by the resistance of the plurality of light-shielding films. That is, great reduction of resistance in the capacitance lines can be made.
Consequently, a storage capacitor is provided to each of the plurality of pixel electrodes by the low-resistance capacitance lines, so even in the event that the driving frequency of the liquid crystal device is increased, sideways cross-talk, ghosting, or the like, due to potential fluctuation of the capacitance line owing to capacitance coupling between the data lines and capacitance lines as in the conventional example described above is reduced, and high-quality image display can be performed. Also, even in the event that the above-described pre-charging method is used, the problems such as with the conventional example do not occur.
Further, the plurality of light-shielding films extend in a direction intersecting with the data lines, which may consist of a plurality of strips of light-shielding film divided in a direction parallel to the data lines so that stress generated during the heating/cooling in the manufacturing process due to differences in the material properties of the films can be markedly relieved in the layered structure formed of the light-shielding film wiring, an inter-layer insulating film, a poly-silicone film, a metal film, and the like, as compared with a case wherein an integrally-formed grid-like, light-shielding film wiring is provided around the opening area for each pixel, for example. Accordingly, cracking of the light-shielding film can be prevented and yield can be improved.
In addition, a redundant structure can be realized, wherein even in the event that a capacitance line is broken due to a foreign object or the like, a plurality of light-shielding films serve in the place of the capacitance line.
With one form of the first liquid crystal device according to the present invention, the above-described light-shielding films are not formed at positions facing the scanning lines, except for positions covering the channel area.
According to this form, capacitance coupling between each of the light-shielding films and each of the scanning lines either hardly occurs for all practical purposes or does no occur at all, so there is no occurrence of potential fluctuation in the light-shielding film owing to change in potential in the scanning lines, and consequently there is no occurrence of potential fluctuation in the capacitance lines.
In order to solve the above problems, a second liquid crystal device according to the present invention may consist of: a plurality of pixel electrodes arrayed in a matrix on one substrate of a pair of substrates between which a liquid crystal is held; a plurality of thin film transistors, each of which drives the plurality of pixel electrodes; a plurality of data lines and plurality of scanning lines mutually intersecting and each connected to the plurality of thin film transistors; a plurality of capacitance lines arrayed along with the plurality of scanning lines and each extending in a direction intersecting with the plurality of data lines, wherein each provides a storage capacitor to the plurality of pixel electrodes; a plurality of light-shielding films, each extending in a direction intersecting with the plurality of data lines, provided at positions so as to cover at least the channel area of the plurality of thin film transistors when viewed from the side of the one substrate and at positions where each at least partially facing the plurality of scanning lines, wherein each is electrically connected with the plurality of capacitance lines for every pixel or plurality of pixels in a direction intersecting with the plurality of data lines; and a first inter-layer insulating film existing between the plurality of light-shielding films and the thin-film transistors.
According to the second liquid crystal device according to the present invention, as with the above-described first liquid crystal device according to the present invention, a plurality of capacitance lines, each of which provides a storage capacitor to a plurality of pixel electrodes, are arrayed along with the plurality of scanning lines and each extending in a direction intersecting with the plurality of data lines. On the other hand, a plurality of light-shielding films, each extends in a direction intersecting with the plurality of data lines, are provided on one substrate at positions so as to cover at least the channel area of the plurality of thin film transistors when viewed from the side of the one substrate. The plurality of light-shielding films are electrically connected to the plurality of capacitance lines for every pixel or plurality of pixels in a direction intersecting with the plurality of data lines. Accordingly, the same operations and advantages as those of the above-described first liquid crystal device according to the present invention can be obtained.
Particularly, with the second liquid crystal device, the light-shielding film is provided on the one substrate at positions at least partially facing the scanning lines. That is, the scanning lines are formed on the light-shielding film at this position, with a first inter-layer insulating film much thicker than the gate insulating film which may consist of the thin-film transistors, for example, introduced therebetween. Accordingly, even in the event that an unintended abnormal formation such as a protrusion or the like happens to be formed on the light-shielding film during the manufacturing process, the probability of this protrusion or the like perforating the first inter-layer insulating film and thereby short-circuiting the scanning lines is vastly reduced. Particularly, in cases wherein a semiconductor layer, a gate insulating film, and capacitance lines are further layered and formed upon such a protrusion formed on the light-shielding film, the configuration according to the second liquid crystal device of the present invention wherein the light-shielding film is formed at positions opposing the scanning lines is more advantageous in terms of improved yield as compared to the above-described first liquid crystal device according to the present invention, when the increase in the probability of this protrusion or the like perforating extremely thin gate insulating film through the semiconductor layer and thereby short-circuiting the semiconductor layer and the capacitance lines is taken into consideration.
According to another form of the first liquid crystal device according to the present invention or to the second liquid crystal device, the capacitance lines and the scanning lines are formed of the same conductive thin film, and the capacitance lines serving as a first storage capacitor electrode and second storage capacitor electrode extending from a semiconductor layer comprising a source or drain area on the side of the thin film transistor connected to the pixel electrode are provided with the storage capacitor by means of being opposingly positioned with a dielectric film which is formed of an insulating film which is the same as the gate insulating film of the thin film transistor being introduced therebetween.
According to this form, the capacitance lines and the scanning lines are formed of the same conductive thin film such as a poly-silicone film, the dielectric film of the storage capacitor and the gate insulating film of the thin film transistor are of the same insulating thin film such as a high-temperature thermal-oxidized film, and the storage capacitor electrodes facing the capacitance lines are formed of a semiconductor layer such as poly-silicone film, so the layered structure formed on the one substrate can be simplified, and further both of the capacitance lines and scanning lines can be formed in the same thin film forming process, or the dielectric film and gate insulating film can both be formed at the same time, which is greatly advantageous from a manufacturing perspective.
With this form, the plurality of light-shielding films may be opposingly positioned as a third storage capacitor electrode at the opposite side of the second storage capacitor electrode with the first storage capacitor electrode and the first inter-layer insulating film introduced therebetween, thereby further providing the storage capacitor.
According to such a configuration, a structure wherein a storage capacitor is provided to both sides across from the first storage capacitor electrode, namely, a double storage capacitor structure is built, so the storage capacitance increases, and functions of preventing flickering and burning of the display image improve.
According to another form of the first or second liquid crystal devices of the present invention, the first inter-layer insulating film is introduced between the capacitance lines and the plurality of light-shielding films, with the plurality of capacitance lines and the plurality of light-shielding films being each electrically connected via contact holes opened in the first inter-layer insulating film for each pixel or plurality of pixels.
According to this form, the plurality of capacitance lines and the plurality of light-shielding films are each electrically connected via contact holes opened in the first inter-layer insulating film for each pixel or plurality of pixels, so a highly reliable electrical connection state can be realized between the two in a sure manner.
The form of the opened contact holes may be such that the contact holes are opened at positions below the data lines when viewed from the side of the other substrate of the pair of substrates.
According to such a configuration, the contact holes are opened at positions below the data lines, namely, the contact holes are away from the pixel portion opening areas, and further, the contact holes are provided to the first inter-layer insulating film portion at which the thin film transistor or the one electrode of the storage capacitor extended from semiconductor layer of the thin film transistor are not formed, and thus effective use of the pixel area can be made.
In the forms of the opened contact holes, the contact holes may have a circular form such as a true circle or an ellipse for the planar form thereof, parallel to the one substrate.
According to such a configuration, in the event that a wet etching process is used as the manufacturing process for opening the contact holes, the probability of the etching solution seeping in at the surface between the plurality of light-shielding films and the neighboring films (namely, the first inter-layer insulating film and the like) so as to cause cracking to be reduced. That is, in the event that one attempts to open contact holes of a square planar form or the like, the solution particularly easily seeps in at the corner portions and also stress tends to be concentrated at such portions, and thus cracking easily occurs at such corners.
In the forms of the opened contact holes, further, each of the plurality of light-insulating films may have a planar form parallel to the one substrate which includes a first area formed parallel to the scanning lines and a second area extended from the first area parallel to the data lines, with the contact holes being opened in the second area.
According to such a configuration, stress placed on the light-shielding film during the manufacturing process can be relieved according to how close the contact holes are opened to the tip of the second area, thereby enabling the prevention of cracking in a more effective manner, and improving yield.
According to another form of the first or second liquid crystal device of the present invention, the capacitance lines and the plurality of light-shielding films are connected to a constant potential source.
According to this form, the plurality of light-shielding films are connected to a constant potential source, so the light-shielding films have a constant potential. Accordingly, change in the potential of the light-shielding film wiring having undesirable effects on the thin film transistors positioned facing the light-shielding films can be prevented. Also, the capacitance lines also have a constant potential, and thus can function as storage capacitor electrodes in a satisfactory manner. In this case, the constant potential of the constant potential source may be equal to the ground potential, for example.
In this form, the configuration may be such that the constant potential source is a constant potential source supplied to peripheral circuit for driving the liquid crystal device.
According to this configuration, the constant potential source is a constant potential source such as a negative power source or positive power source supplied to peripheral circuit such as the scanning line driving circuit or data line driving circuit, and thus there is no need to provide special potential wiring or external circuit connection terminals, and the light-shielding films and capacitance lines can be easily be made to have a constant potential.
Or, the configuration may be such that an opposite electrode is formed on the other substrate of the pair of substrates, such that the constant potential source is a constant potential source supplied to the opposite electrode.
According to this configuration, the constant potential source is a constant potential source such as a negative power source or positive power source supplied to the opposite electrode, and thus there is no need to provide special potential wiring or external circuit connection terminals, and the light-shielding films and capacitance lines can be easily be made to have a constant potential.
According to another form of the first or second liquid crystal device of the present invention, each of the plurality of light-shielding films are each electrically connected to the capacitance lines for forming a storage capacitor given to pixels of neighboring tiers, either the preceding tier or the following tier.
According to this configuration, the offset at the area along the edge of the opening area of the pixel where the pixel TFTs, capacitance lines, and light-shielding films are formed over the data lines can be made smaller with regard to other areas, as compared with cases wherein each of the plurality of light-shielding films are each electrically connected to their own capacitance lines, namely, electrically connected to capacitance lines for providing a storage capacitor to pixel electrodes connected to TFTs with the channel area thereof positioned over the light-shielding films. Now, the term neighboring capacitance line, or capacitance line of previous or following tier refers to a capacitance line for providing a storage capacitor to a pixel electrode neighboring a capacitance line for forming a storage capacitor to be provided to pixel electrodes connected to TFTs with the channel area thereof positioned over the light-shielding films. In the case that the offset is small, as in this case, liquid crystal disclination (defective alignment) of the liquid crystal caused by the offset can be reduced.
According to another form of the first or second liquid crystal device of the present invention, each of the plurality of light-shielding films are each electrically connected to the capacitance lines of its own tier.
According to this configuration, the offset where the pixel TFTs, capacitance lines, and light-shielding films are formed over the data lines increases, but the capacitance lines and light-shielding films can be electrically connected relatively easily, by contact holes and the like.
This form may be configured so as to further comprise a second inter-layer insulating film provided above the scanning lines and below the data lines, and a third inter-layer insulating film provided above the data lines and below the pixel electrodes, wherein the side of the third inter-layer insulating film which faces the liquid crystal is flattened by means of at least one of the first, second, and third inter-layer insulating films being recessed at least portions facing the data lines.
According to this configuration, at least one of the first, second, and third inter-layer insulating films are recessed at least portions facing the data lines, and thus the offset where the pixel TFTs, capacitance lines, and light-shielding films are formed over the data lines can be reduced with regard to other areas. The side of the third inter-layer insulating film which faces the liquid crystal is thus flattened, so disclination (defective alignment) of the liquid crystal caused by unevenness on the surface of the third inter-layer insulating film can be reduced according to the degree of this flattening.
With another form of the first or second liquid crystal device according to the present invention, the plurality of light-shielding films include at least one-of the following: Ti (titanium), Cr (chromium), W (tungsten), Ta (tantalum), Mo (molybdenum), and Pb (lead).
According to this form, the light-shielding films are formed of a single metal, alloy, metal silicide, or the like, including at least one of the following non-transparent metals with high melting points: Ti, Cr, W. Ta, Mo, and Pb. Accordingly, the light-shielding films are formed so as to not be damaged or melt during the high-temperature processing in the TFT formation process performed following the process of forming the light-shielding films on the TFT array substrate.
The present invention is a projection-type display apparatus which has a light source, a liquid crystal light valve for performing modulation to incident light cast from the light source according to image information, and projecting element for projecting the light modulated by the liquid crystal light valve; wherein the liquid crystal light valve has a liquid crystal device in which a liquid crystal is held between a first substrate positioned at the light incident side and a second substrate positioned at the light outgoing side, a first polarizing element positioned at the outward side of the first substrate, and a second polarizing element positioned at the outward side of the second substrate; and wherein the following are provided upon the second substrate: a plurality of pixel electrodes arrayed in a matrix on the second substrate; a plurality of thin film transistors, each of which drives the plurality of pixel electrodes; a plurality of data lines and plurality of scanning lines mutually intersecting and each connected to the plurality of thin film transistors; a plurality of capacitance lines arrayed along with the plurality of scanning lines and each extending in a direction intersecting with the plurality of data lines, wherein each provide a storage capacitor to the plurality of pixel electrodes; a plurality of light-shielding films, each extending in a direction intersecting with the plurality of data lines, and provided at positions so as to cover at least the channel area of the plurality of thin film transistors when viewed from the side of the one substrate and at positions each at least partially facing the plurality of capacitance lines, wherein each is electrically connected with the plurality of capacitance lines for every pixel or plurality of pixels in a direction intersecting with the plurality of data lines; and a first inter-layer insulating film existing between the plurality of light-shielding films and the thin-film transistors.
According to this form, leak current owing to returning light can be prevented by forming a light-shielding film between the second substrate and thin-film transistor. Also, since effects of the returning light to the liquid crystal device can be prevented, there is no need to apply a polarizing element with a reflection-preventing film onto the liquid crystal device as with conventional arrangements, and clearance formation can be realized, so temperature increase in the liquid crystal device can be prevented.
In order to solve the above problems, a third liquid crystal device according to the present invention may consist of: a plurality of pixel electrodes arrayed in a matrix on one substrate of a pair of substrates between which a liquid crystal is held; a plurality of thin film transistors, each of which drives the plurality of pixel electrodes; a plurality of data lines and plurality of scanning lines mutually intersecting and each connected to the plurality of thin film transistors; a plurality of capacitance lines formed along with the plurality of scanning lines, each for providing a storage capacitor to the plurality of pixel electrodes; conductive light-shielding films provided at positions so as to cover at least the channel area of the plurality of thin film transistors when viewed from the side of the one substrate, wherein each includes a wiring portion extended along with the scanning lines and is electrically connected to the plurality of capacitance lines; and a first inter-layer insulating film existing between the light-shielding films and the thin-film transistors.
According to the liquid crystal device of the present invention, light-shielding films are provided at positions so as to cover at least the channel area of the plurality of thin film transistors when viewed from the side of the one substrate. Accordingly, the channel area of the thin film transistors is shielded from light by light-shielding films regarding returning light cast in from the side of the one substrate, thereby preventing deterioration of the properties of the thin film transistors due to returning light and the like. On the other hand, the capacitance lines are formed parallel to a plurality of scanning lines, with these capacitance lines and the conductive light-shielding films including the wiring portions extended parallel to the scanning lines being electrically connected. Accordingly, the resistance of the capacitance line can be markedly lowered by the resistance of the conductive light-shielding films. For example, by forming the capacitance lines from a poly-silicone film and forming the plurality of light-shielding films from a conductive metal film with a high melting point, the resistance of the capacitance lines in the direction parallel to the scanning lines can be governed by the sheet resistance of the plurality of light-shielding films. That is, the resistance of at the capacitance lines can be greatly reduced.
Consequently, a storage capacitor is provided to each of the plurality of pixel electrodes by the low-resistance capacitance lines, so even in the event that the driving frequency of the liquid crystal device is increased, sideways cross-talk, ghosting, or the like, due to potential fluctuation of the capacitance line owing to capacitance coupling between the data lines and capacitance lines as described above is reduced, and high-quality image display can be performed.
In addition, a redundant structure can be realized, wherein even in the event that a capacitance line is broken due to a foreign object or the like, a plurality of light-shielding films serve in the place of the capacitance line.
With a form of the third liquid crystal device according to the present invention, the capacitance lines and the scanning lines are formed of the same conductive thin film, and the capacitance lines serving as one storage capacitor electrode and the other storage capacitor electrode extending from a semiconductor layer which may consist of a source or drain area of the side of the thin film transistor connected to the pixel electrode may consist of a storage capacitor by means of being opposingly positioned with a dielectric film which is formed of an insulating film which is the same as the gate insulating film of the thin film transistor being introduced therebetween.
According to this form, the capacitance lines and the scanning lines are formed of the same conductive thin film such as a poly-silicone film or the like, the dielectric film of the storage capacitor and the gate insulating film of the thin film transistor are of the same insulating thin film such as a high-temperature thermal-oxidized film or the like, and the storage capacitor electrodes facing the capacitance lines are formed of a semiconductor layer portion such as poly-silicone film or the like, so the layered structure formed on the one substrate can be simplified, and further, both the capacitance lines and scanning lines can be formed in the same thin film forming process, or the dielectric film and gate insulating film can both be formed at the same time, which is greatly advantageous from a manufacturing perspective.
With another form of the third liquid crystal device according to the present invention, the first inter-layer insulating film is introduced between the capacitance lines and the light-shielding films, and the capacitance lines and the light-shielding films are each connected via contact holes opened in the first inter-layer insulating film.
According to this form, the capacitance lines and the light-shielding films are each connected via contact holes opened in the first inter-layer insulating film, so a highly reliable electrical connection state can be realized between the two in a sure manner.
With another form of the third liquid crystal device according to the present invention, the contact holes are opened for each pixel.
According to this form, the capacitance lines and the light-shielding films are each connected via contact holes opened for each pixel, so lowering of the resistance of the capacitance lines by the light-shielding film can be promoted, and further, the degree of redundancy in structure between the two can be increased.
With another form of the third liquid crystal device according to the present invention, the contact holes are opened for each pixel group formed of a plurality of pixels.
According to this form, the capacitance lines and the light-shielding films are each connected via contact holes opened for each pixel group formed of a plurality of pixels, so the advantages of lowering the resistance of the capacitance lines by the light-shielding film, and of the redundant structure can be appropriately balanced with the complexity in the manufacturing process or with problems such as defective liquid crystal devices, while giving consideration to the sheet resistance of the capacitance lines and light-shielding film, the driving frequency and required specifications and the like thereof, and thus is extremely advantageous in practical implementations.
With another form of the third liquid crystal device according to the present invention, the contact holes are opened below the data lines when viewed from the side of the other substrate of the pair of substrates.
According to this form, the contact holes are opened below the data lines. That is, the contact holes are away from the pixel portion opening areas, and further, the contact holes are provided to the first inter-layer insulating film portion at which the thin film transistor or the one electrode of the storage capacitor extended from semiconductor layer of the thin film transistor are not formed, so effective use of the pixel area can be made.
With another form of the third liquid crystal device according to the present invention, the capacitance lines and the light-shielding films are connected to a constant potential source.
According to this form, the light-shielding films are connected to a constant potential source, so the light-shielding films have a constant potential. Accordingly, change in the potential of the light-shielding films having undesirable effects on the thin film transistors positioned facing the light-shielding films can be prevented. Also, the capacitance lines also have a constant potential, and thus can function as storage capacitor electrodes in a satisfactory manner. In this case, the constant potential of the constant potential source may be equal to the ground potential, for example.
With another form of the third liquid crystal device according to the present invention, the constant potential source is a constant potential source supplied to peripheral circuit for driving the liquid crystal device.
According to this form, the constant potential source is a constant potential source such as a negative power source or positive power source supplied to peripheral circuit such as the scanning line driving circuit, data line driving circuit, or sampling circuit, so the light-shielding films and capacitance lines can be made to have constant potentials without providing special potential wiring or external circuit connection terminals.
With another form of the third liquid crystal device according to the present invention, an opposite electrode is formed on the other substrate of the pair of substrates, and the constant potential source is a constant potential source supplied to the opposite electrode.
According to this form, the constant potential source is a constant potential source such as a negative power source or positive power source supplied to the opposite electrode, thus the light-shielding films and capacitance lines can be made to have a constant potential without providing special potential wiring or external circuit connection terminals.
With another form of the third liquid crystal device according to the present invention, the capacitance lines include wiring portions each formed parallel to the plurality of scanning lines, and the light-shielding films include wiring portions formed parallel to the scanning lines so as to each appear overlapped when the capacitance line portion is viewed from the side of the one substrate.
According to this form, the wiring portions of the capacitance lines, each being formed parallel to the plurality of scanning lines:, and the wiring portions of the light-shielding films formed parallel to the scanning lines are mutually electrically connected, the resistance of the capacitance lines can be reduced in the direction parallel to the scanning lines, and also the degree of redundancy of the above-described redundant structure of the capacitance lines can particularly be increased in the direction parallel to the scanning lines.
With another form of the third liquid crystal device according to the present invention, the light-shielding films are provided in a screen-like manner at positions so as to each appear overlapped with at least one of the plurality of scanning lines and the plurality of capacitance lines, and the plurality of data lines when viewed from the side of the one substrate.
According to this form, the light-shielding films are provided in a screen-like manner, so-lowering of the resistance of the electrically-connected capacitance lines by the light-shielding film can be promoted, and further, the degree of redundancy in structure between the two can be increased.
With another form of the third liquid crystal device according to the present invention, the light-shielding films are provided in strips at positions so as to each appear overlapped with at least one of the plurality of scanning lines and the plurality of capacitance lines when viewed from the side of the one substrate.
According to this form, the light-shielding films are provided in strips, so lowering of the resistance of the electrically-connected capacitance lines by the light-shielding film, especially in a direction along with the scanning line, can be promoted, and further, the degree of redundancy in structure between the two can be increased.
With another form of the third liquid crystal device according to the present invention, the light-shielding films are provided in an island-like manner at positions so as to each appear overlapped with at least one of the plurality of scanning lines and the plurality of capacitance lines when viewed from the side of the one substrate, and each of the plurality of the island-shaped portions arrayed parallel to the scanning lines are mutually electrically connected via the capacitance lines.
According to this form, the light-shielding films are provided in an island-like manner, and the plurality of the island-shaped portions arrayed parallel to the scanning lines are mutually electrically connected via the capacitance lines, thus lowering of the resistance of the electrically-connected capacitance lines by the light-shielding film can be promoted, and further, the degree of redundancy in structure between the two can be increased.
With another form of the third liquid crystal device according to the present invention, the light-shielding films are provided in strips parallel to the data lines.
According to this form, formation can be made without lowering the opening ratio, by means of extending along the data lines. Further, in the event that the light-shielding films are formed parallel to the scanning lines or capacitance lines for example, a contact hole is often formed nearby which brings a pixel electrode and the semiconductor layer into contact. At this time, there is the danger of the stress of the light-shielding film suppressed by the inter-layer insulating film being discharged by the opening of the contact hole between the pixel electrode and the semiconductor layer near the light-shielding film, and it causes cracking in the light-shielding films. However, in the event that the light-shielding films are formed parallel to the data lines, the light-shielding films can be removed from the contact hole between the pixel electrode and the semiconductor layer, so the effects of stress of the light-shielding film can be relieved as much as possible. Also, connecting the light-shielding films parallel to the data lines to the capacitance lines enables reduction in resistance of the capacitance lines.
With another form of the third liquid crystal device according to the present invention, the light-shielding films are connected to a constant potential source.
According to this form, change in the potential of the light-shielding films having undesirable effects on the thin film transistors positioned facing the light-shielding films can be prevented.
With another form of the third liquid crystal device according to the present invention, the light-shielding films include at least one of the following: Ti, Cr, W, Ta, Mo, and Pb.
According to this form, the light-shielding films are formed of a single metal, alloy, metal silicide, or the like, including at least one of the following non-transparent metals with high melting points: Ti, Cr, W, Ta, Mo, and Pb. Accordingly, the light-shielding films are formed so as to not be damaged or melt during the high-temperature processing in the TFT formation process performed following the process of forming the light-shielding films on the TFT array substrate.
Another form of the third liquid crystal device according to the present invention may further consist of a second inter-layer insulating film provided above the scanning lines and below the data lines, and a third inter-layer insulating film provided above the data lines and below the pixel electrodes; wherein the side of the third inter-layer insulating film which faces the liquid crystal is flattened by means of at least one of the first, second, and third inter-layer insulating films being recessed at portions facing at least one of the thin film transistors, the data lines, the scanning lines, and the capacitance lines.
With another form of the third liquid crystal device according to the present invention, the side of the third inter-layer insulating film which faces the liquid crystal is flattened by means of at least one of the first, second, and third inter-layer insulating films being recessed, thus disclination (defective alignment) of the liquid crystal caused by unevenness on the surface of the third inter-layer insulating film can be reduced according to the degree of this flattening.
The present invention is electronic equipment comprising the third liquid crystal device.
According to this form, the electronic equipment has the liquid crystal device according to the invention of the present application, so image display with high quality can be realized with a liquid crystal device which has high reliability due to the redundant structure, reduced display deterioration such as sideways cross-talk, and superb light-shielding capabilities regarding returning light and the like.
Such operations and other advantages of the present invention will become clear from the embodiments described next.